Device for treating objects by plasma deposition

ABSTRACT

A device for treating objects by plasma deposition, comprising: 
         a sealed treatment chamber ( 1 ), at a reduced pressure, provided on one of its walls ( 4 ) with a passage ( 2 ) that can be closed off, said passage ( 2 ) allowing objects for treatment ( 3 ) to be conveyed into and out of the treatment chamber ( 1 ),    a transfer space ( 5 ) which can be placed, via said passage ( 2 ), in communication with the treatment chamber ( 1 ) so that objects for treatment ( 3 ) are introduced into the transfer space ( 5 ) prior to being introduced into the treatment chamber ( 1 ), 
 
the device being characterized in that the transfer space ( 5 ): 
   is delimited by discontinuous walls ( 6,7 ),    is able to move relative to the treatment chamber ( 1 ) so as to be able to negotiate the passage ( 2 ) of the treatment chamber ( 1 ).

FIELD OF THE INVENTION

The present invention relates to a device for treating objects by plasma deposition. The objects for treatment may for example be tube components such as bodies, shoulders or stoppers.

It relates more precisely to an assembly consisting of a treatment chamber and of a transfer space placed in communication with the treatment chamber. The object or objects for treatment passing into the transfer space prior to being introduced into the treatment chamber, the treatment being performed at a reduced pressure.

STATE OF THE ART

American Patent U.S. Pat. No. 4,816,638 describes a treatment chamber for plasma deposition. The treatment chamber being placed in communication with a transfer chamber acting as a lock chamber. American Patent U.S. Pat. No. 4,861,563 describes an assembly comprising a mobile treatment chamber arranged inside a transfer chamber.

The devices of the prior art, although usable in automatic systems, are relatively complicated to produce and the treatment of objects is characterized by a high number of steps, hence a relatively lengthy time taken to treat a given object.

It is therefore desirable to have a treatment chamber/transfer chamber system that performs better.

SUMMARY OF THE INVENTION

The disadvantages noted in the previous chapter are avoided by virtue of the present invention which relates to a device for treating objects by plasma deposition, comprising:

-   -   a sealed treatment chamber, at a reduced pressure, provided on         one of its walls with a passage that can be closed off, said         passage allowing objects for treatment to be conveyed into and         out of the treatment chamber,     -   a transfer space which can be placed, via said passage, in         communication with the treatment chamber so that objects for         treatment are introduced into the transfer space prior to being         introduced into the treatment chamber, the invention is         particularly characterized in that the transfer space:     -   is delimited by discontinuous walls,     -   is able to move relative to the treatment chamber so as to be         able to negotiate the passage of the treatment chamber.

As will be seen hereinafter, the transfer space has a dual function: that of acting as a support when the objects for treatment are being transferred and that of acting as a lock chamber when it is in a particular position.

This dual function considerably simplifies the design of the device. Furthermore, the device according to the invention is particularly well suited to automated use.

The invention can be read across to a great many alternative forms.

The transfer space may be moved by a drive system arranged outside the treatment chamber, near its passage.

The drive system may just as easily be designed so that it passes completely through the treatment chamber.

According to a preferred embodiment, part of the walls delimiting the transfer space is designed to close off the passage of the treatment chamber.

According to a particularly advantageous alternative embodiment of the invention, the passage of the treatment chamber is extended outside the latter so as to form a hollow body, for example a cylindrical one, the side walls of which are sealed.

The walls delimiting the transfer space are chosen and sized so that as the transfer space moves in the hollow body, a temporary moving lock chamber is formed.

The walls delimiting the transfer space may be fixed together, for example by means of a rod connecting them, the entity being secured to a drive system such as a telescopic system.

As a preference, the walls delimiting the transfer space are fixed independently of one another to the drive system which consists for example of a frame designed to slide in a direction parallel to the movement of the transfer space. This configuration allows the transfer space to be completely devoid of any object other than the objects for treatment.

According to a particularly advantageous configuration of the invention, the walls delimiting the transfer space consist of two parallel disks, the transfer space corresponding to the volume which lies between the two disks. Each disk is fixed at its outer face to a member forming part of the drive system.

As has been seen, the invention is particularly characterized in that the treatment chamber and the transfer space are able to move one relative to the other, which means that it is possible to have a configuration in which the treatment chamber is fixed and the treatment space can move or, conversely, the treatment chamber can move and the treatment space is fixed.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described in greater detail hereinafter by means of the following figures:

FIG. 1 shows a front view of a first embodiment of the invention.

FIG. 2 shows a top view of the embodiment of FIG. 1.

FIG. 3 shows a front view of a second embodiment of the invention.

FIG. 4 shows a front view, in a first position, of a third embodiment of the invention.

FIG. 5 shows a front view, in a second position, of the embodiment of FIG. 4.

FIG. 6 shows a front view, in a third position, of the embodiment of FIG. 4.

FIG. 7 shows a top view of the embodiment of FIGS. 4 to 6.

Each element common to each figure bears the same numerical reference.

The device illustrated in FIG. 1 comprises a sealed treatment chamber 1 which contains elements (not illustrated) but allows a vacuum to be set up therein and allows one or more objects 3 to be treated by plasma deposition. In its top wall 4, the treatment chamber 1 is provided with a passage 2 connecting the inside of the chamber with the outside.

As can be seen in FIG. 2, the treatment chamber 1 is of circular shape, as is the cross section of its passage 2. Passage 2, which forms a hollow cylinder, extends toward the inside of the treatment chamber 1.

Arranged outside the treatment chamber 1, in the extension of the passage 2, is a transfer space 5 delimited by two parallel circular walls 6,7, fixed together at their centers by means of a rod 11. The upper disk 6 being fixed to a telescopic spindle 9 able to be actuated by a motor (not illustrated). The telescopic spindle 9 is itself fixed to an armature 12 arranged above the device.

The device illustrated in FIG. 3 is identical to the one in FIGS. 1 and 2 except that the telescopic spindle and its motor are arranged under the device, the telescopic spindle passing in a sealed fashion through the bottom wall of the treatment chamber.

The device illustrated in FIGS. 4 to 7 also have several points in common with the devices of the preceding figures. It does, however, differ in that the disks 6, 7 delimiting the transfer space 5 are fixed independently of one another to a sliding frame 10 which extends on each side of the treatment chamber 1. The bottom disk 7 in fact forms the upper part of a cylinder 12 which forms part of a sliding frame. In its bottom wall 14, the treatment chamber 1 is provided with an opening 13 the section of which is more or less equal to the diameter of the disks 6,7. The length of the cylinder 12, which may be hollow or solid, is such that as it moves, it constantly closes off the opening 13 arranged in the bottom wall 14 of the treatment chamber 1.

The device illustrated in FIGS. 4 to 7 works as follows:

In a first step, illustrated in FIG. 4, objects for treatment 3 are placed, for example with the aid of a robot arm, on the face of the bottom disk 7 which is on the same side as the transfer space 5. The sliding frame 10 is then lowered to a position illustrated in FIG. 5. At this instant, the transfer space 5 is completely delimited by the disks 6, 7 and the wall of the extension 8. In this particular position, the transfer space 5 and the walls delimiting it form a sealed compartment acting as a lock chamber. Optionally, means 15 may be provided for producing a total or partial vacuum in the lock chamber.

The above mentioned “lock-chamber” phase may occur dynamically, that is to say without interruption of the movement of the sliding frame 10 downward. It is also possible for the descent of the sliding frame 10 to be interrupted temporarily when the lock chamber is formed, particularly if there is a desire to set up a vacuum in the lock chamber.

FIG. 6 illustrates the situation in which the transfer space 5 is completely included inside the treatment chamber 1. It should be pointed out, at this stage, that the top disk 6 is in complete contact with the top wall 4 of the treatment chamber 1 so as to produce perfect sealing within this chamber. At this moment, the objects 3 can be treated. Means (not illustrated) arranged in the treatment chamber can generate a plasma so as to coat the surface of the objects 3 with a thin layer acting, for example, as an anti-diffusion layer. One the objects 3 have been treated, the reverse steps to those previously described are carried out so as to return the device to a configuration identical to the one illustrated in FIG. 4. The treated objects 3 are then removed from the transfer space 5 and replaced with new objects 3 for treatment. The treatment cycle can then continue immediately.

From the abovementioned examples it can be seen in particular that the invention has a particularly beneficial advantage: whatever the position of the transfer space, there is always equilibrium between the pressure forces exerted on the top and bottom disks. The result of this is that the energy needed to move the transfer space is minimal and that this inventive concept also works during transfer into a treatment chamber at a pressure higher than atmospheric pressure.

It goes without saying that the invention is not restricted to the examples described hereinabove.

As mentioned, there are a great many alternative forms of embodiment which form part of the inventive concept.

Particular note will be made of the following points:

-   -   the cross section of the passage of the treatment chamber and         its extension is not necessarily circular, a square cross         section for example would achieve the same goal.     -   it is just as possible to envision a transfer space closed on         most of its periphery, with an opening of a size just large         enough to allow the objects for treatment to be introduced and         removed. Thus, it is possible to conceive of a transfer space         lying inside a sliding cylinder, the latter being provided with         a small-sized opening on its side wall.     -   the distance between the disks must make it possible to obtain a         “lock-chamber” phase. As a preference, this distance is         minimized so as to reduce the variation in pressure resulting         from the transfer space being placed in contact with the space         situated inside the treatment chamber.     -   the geometry of the bottom disk can be produced in such a way as         to ensure a progressive (gradual) vacuum in the transfer space         as the transfer space is placed in contact with the treatment         chamber. One way of achieving this characteristic would consist         in using a disk the top face of which, on part of its periphery,         was inclined downward. 

1. A device for treating objects by plasma deposition, comprising: a sealed treatment chamber (1), at a reduced pressure, provided on one of its walls (4) with a passage (2) that can be closed off, said passage (2) allowing objects for treatment (3) to be conveyed into and out of the treatment chamber (1), a transfer space (5) which can be placed, via said passage (2), in communication with the treatment chamber (1) so that objects for treatment (3) are introduced into the transfer space (5) prior to being introduced into the treatment chamber (1), the device being characterized in that the transfer space (5): is delimited by discontinuous walls (6,7), is able to move relative to the treatment chamber (1) so as to be able to negotiate the passage (2) of the treatment chamber (1).
 2. The device as claimed in the preceding claim, characterized in that at least part of the walls (6,7) delimiting the transfer space (5) is designed to close off the passage (2) of the treatment chamber (1).
 3. The device as claimed in the preceding claim, characterized in that the passage (2) of the treatment chamber (1) is extended outside the treatment chamber (1) so that the extension (8) allows the transfer space (5) to be converted into a lock chamber when this transfer space (5) moves inside the extension (8).
 4. The device as claimed in the preceding claim, characterized in that the walls (6, 7) delimiting the transfer space (5) are fixed together, the entity being secured independently of one another to a drive system (9).
 5. The device as claimed in any one of claims 1 to 3, characterized in that the walls (6, 7) delimiting the transfer space (5) are secured to a sliding frame (10).
 6. The device as claimed in any one of the preceding claims in which the treatment chamber (1) is fixed and the transfer space (5) can move.
 7. The device as claimed in any one of the preceding claims in which the treatment chamber (1) can move and the transfer space (5) is fixed.
 8. A method of using the device as claimed in any one of the preceding claims, characterized by the following steps: depositing one or more objects for treatment (3) on one of the discontinuous walls (6, 7) delimiting the transfer space (5), relative moving of said walls (6,7) and of the transfer space (5) toward the treatment chamber (1), possibly setting up a vacuum when the objects are in said lock chamber, relative moving of said walls (6, 7) and of the transfer space (5) inside the treatment chamber (1), treating the object or objects (3), relative moving of said walls (6, 7) and of the transfer space (5) toward the outside of the treatment chamber (1), removing the object or objects (3) from the transfer space (5). 